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Canadian  Institute  for  Historical  Microreproductions  /  Institut  canadien  de  microreproductions  historiques 


Technical  and  Bibiiogruphic  Notes/Notes  techniques  et  bibliographiques 


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I    Bound  with  other  material/ 
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D 


D 


0 


Tight  binding  may  causa  shadows  or  distortion 
along  interior  margin/ 

Lareliure  serree  peut  causer  de  I'ombre  ou  de  la 
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The 
to  tl 


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E    Pages  discoloured,  stainud  or  foxed/ 
Pages  d^colordes,  tachetdes  ou  piqui 


The 
post 
of  tl 
film 


Oris 

begi 

the 

slon 

oth< 

first 

sion 

or  il 


piquees 


I      I    Pages  detached/ 


Pages  d^tachees 

Showthrough/ 
Transparence 

}f  prir 

nigale  de  I'impression 

supplementary  materia 
Comprend  du  materiel  suppiementaire 

idition  available/ 
Edition  disponible 


I    ~|    Showthrough/ 

□    Quality  of  print  varies/ 
Quality  inigale 

I      I    Includes  supplementary  material/ 

□    Only  edition  available/ 
Seule 


The 
shal 
TINI 
whii 

Mbf 
difff 
entli 
begi 
righ 
reqi 
met 


n 


Pages  wholly  or  partially  obscured  by  errata 
slips,  tissues,  etc..  have  been  rafilmed  to 
ensure  the  best  possible  image/ 
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Additional  comments:/ 
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This  item  is  filmed  at  the  reduction  ratio  checked  below/ 

Ce  document  est  fiim^  uu  taux  de  reduction  indiquA  ci-dessous. 

10X  14X  18X  22X 


26X 


30X 


12X 


16X 


20X 


24X 


28X 


32X 


The  copy  filiied  here  has  been  reproduced  thanks 
to  the  generosity  of: 

Library, 

Geological  Survey  of  Canada 


L'exemplaire  filmt  fut  reproduit  grAce  d  la 
g6n6rosit4  de: 

Bibliothique, 

Commission  G6ologtque  du  Canada 


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conformity  avec  les  conditions  du  contrat  de 
filmage. 


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la  derniAre  page  qui  comporte  une  telle 
empreinte. 


The  last  recordeo  frame  on  each  microfiche 
shall  contain  the  symbol  —^-(meaning  "CON- 
TINUED"), or  the  symbol  V  (meaning  "END  "), 
whichever  applies. 


Un  des  symboles  suivants  apparaitrc  sur  la 
dernidre  image  de  cheque  microfiche,  selon  le 
cas:  le  symbols  —^  signifie  "A  SUIVRE",  le 
symbols  y  signifie  "FIN  ". 


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different  reduction  ratios.  Tho&e  too  large  to  be 
entirely  included  in  one  exposure  are  filmed 
beginning  in  the  upper  left  hand  corner,  left  to 
right  and  top  to  bottom,  as  many  frames  as 
required.  The  following  diagrams  illustrate  the 
method: 


Les  cartes,  planches,  tableaux,  etc.,  peuvent  §tre 
fiimis  d  des  taux  de  rdduction  diffdrents. 
Lorsque  le  document  est  trop  grand  pour  dtre 
reproduit  en  un  seul  ciichd,  il  est  film6  d  partir 
de  I'angle  supdrieur  gauche,  de  gauche  d  droits, 
et  de  haut  en  bas,  en  prenant  le  nombre 
d'images  nicessaire.  Les  diagrammes  suivants 
illustrent  la  mdthode. 


1  2  3 


1 

2 

3 

4 

5 

6 

BULLETIN   OF  THE   GEOLOGICAL   SOCIETY   OF   AMERICA 

Vol.  9,  pp.  223-238 


CLASTIC  HURONIAN  ROCKS  OF  WESTERN  ONTARIO 


BV 


ARTL.  :l  P.  COLEMAN 


^^y^^try. 


ROCHESTER 

PUBLISHED  BY  THE  S0CIP:TY 

February,  1898 


BULLETIN  OF  THE  GEOLOGICAL  SOCIETY  OF  AMERICA 

VOL.  9,   PP.  223-23«  FbBRUARV  2.,   ,«3« 


CLASTIC  IICUOMAN   RuCKS  OK  WKSTKIJX  ONTARIO 

i!V  .virnni!  p.  coi.kma.n 

{Read  hrfore  the  Snnclij  Thrvmhcr  J!),  1S!)7) 

(X)NTKNTS 

Ua«iiItH  (,f  provioiiH  work  in  tlio  region.  ''"»■"■ 

t;iiissifi,.ati,,ii  of  (he  rofk  .-^erioK,  .."... "•' 

Huroniiin  clustic's ~-^ 

< ioneral  .stati'incnf  a.s  to  origin ..'''',\\ "■* 

KiHMvatin  rocks —-♦ 

Conch  idling  rocks ,  \\ --''' 

Helation  of  K.>(>watin  to  Concl, idling' "" 

Tiiickiici^s  of  till!  Hiironian  scries  "'' 

Field  relations  of  Lanrentian  and  Hnr.'.niaii "^ 

Sections  tliro.igh  |.re-ranil.rian  .no.intains.  "" 

(n'ologicalhistory  of  the  re-ion -•'" 

Comparison  with  oth--  regions -•'' 

Cause  of  these  mountain  structures  .      -''- 

Kxtent  of  the  hatholitic  region -■'•' 

Concluding  ohservatioiis  ■'   '      -•'•"' 

2;!S 


Kksults  of  |'k,.;vi...-s  uokic  rx  tuk  Rk(ii..n 

.    The  -odes  of  we.ster.1  Ontario  have  been  more  or  loss  carefullv  ex.n» 
nK.l     y  several  .eolo.ists,  sueh  as  J.,sl>v,  Hell,  and   I^t  \^X 

y  t' hv"^ r  7T' "  "T  •  ?'"  "■'•^ '''''' '' ''''  '-'^'  ->--^  ^ 

St!    V    n      V         T!'  ";  '"  '""'  ""  '""''^^'"'^  fottndation  for  the  future 
tn.ly  of  the  Lake  ot  the  Woods  and  Rainy  Lake  districts.*    Since      e 
a«llo.nn,,  .hstncts  have  been  ,nap,.ed  hy  W.  If.  r.  Smith  and         Vd 
ne^  and  specuU  portions  have  been  studied  bv  H.  L.  Sn.^th    Winctn 
and  Grant,  and  the  prese.tt  writer.      The  ,eneral  eonehtsion    ;!'         b v 
Lawson  have  been  eo.nn.only  aceepte.l  by  those  who  have  followed  an  1 
wUHu^ade  use  of  largely  in  the  present  paper,  though  .no     o    th 


*ii.M,|.Surv,.y„rc,miul,.,lss;^,  ,„„•((■(■;  un.i  [s^.i^i^uy 
XXXIV-Bn.i..  (iKui..  .s,„.  .\.M.,  V(,i.  -J,  1SU7. 


{2L';i) 


224 


A.   v.  COI.KMAN — CI.ASTIC    II  li«  >NI  AN     KocKS, 


facts  cmployiMl  lum-  Lccn  ..l.s,.nT.l  l.y  tlir  writer  wl.il.-  .■n-ii.inl  in  lifl.l 
work  for  tlic  Oiitjirio  Hiirciiu  of  Mines. 

('l.AS-^Il'IfAIMnN    <>:•    I'lIK    IJotK    SkHIKS 

r.awson  .les.Tihes  tl.c  n-ion  as  wholly  Aivhean.  and  .livi.les  the  rocks 
into  two  i)arls-a  lower  one,  the  l.aurcntian,  an-l  an  npi.er  (.nc,  the  Onta- 
rian,  further  subdivide.!  into  the  Coucliiching  and  the  Keewalin.  'I  he 
tenn  Laurentian  is  used  here  in  a  petroKrai-liic  sense,  to  denote  a  series 
of  entirely  crvstalline,  <ienerally  acid,  rocks,  esi-ecially  coarse-  grained 
jrueisses  and  jiranites,  in  spite  of  the  fact  that  these  rocks  have  an  oruptivo 
contact  with  the  overly  inj:  series,  and  so  are  later  in  a-je  than  the  Ontanan. 
The  fouchichinu  rocks,  found  chielly  in  the  southern  portion  ol  the 
reuMon  alon.i,'  the  boundary  of  Miiniesota,  consist  in  general  <.f  nionot- 
on'ous  grav  or  hrown  micaschists  and  gneisses,  sedimentary  in  origin. 

The"Keewatin.  wlii.'h  overlies  the  Couehiching  where  the  latter  is 
present  and  in  other  cases  rests  on  the  I>aurentian.  is  largely  composed 
of  eruptives  and  their  products-schists  resulting  from  shearing,  ash 
rocks,  and  aiiglomerates— basic  in  the  lower  part,  acid  in  the  upper.* 

Lawson  d()cs  not  delinitelv  correlate  the  Couehiching  with  either  the 
Laurentian  or  lluronian,  but  Van  11  ise  includes  at  least  part  of  it  in  the 
HasenientCon.plex.t  l.awson  puts  the  Keewatin  doubttuUy  with  the 
lluronian.  pointing  out  numerous  dilVerences between  it  and  the  original 
lluronian  as  described  by  Logan.  In  general,  however,  Canadian  geol- 
ogists .lo  not  hesitate  to  class  these  altered  eruptives  and  the  accompany- 
ing sedimentary  rocks  as  lluronian.  and  this  usage  will  be  followed  m  the 

present  paper. 

In  the  first  place  the  lluronian  clasti<-s  will  be  briefly  descrilxxl,  and 
afterwards  the  relations  subsisting  l)etween  the  series  of  rocks  and  their 
causes  will  be  discussed.  The  term  .\rchean  will  be  used  to  include  both 
Laurentian  and  lluronian  (,or  Ontarian), though  according  to  the  classi- 
fication adoi)ted  by  the  United  States  (ieological  Survey  the  latter  would 
be  included  in  the  .Mgonkian. 

lllKOMAN   Ci.Asru's 

(iE.\Eirii.  ■•^rAri-:Mi-:.\r  AS  yo  o/,'/(,/.v 

As  to  origin,  the  .Archean  <'lastic  rocks  of  western  Ontario  are  of  three 
kin.ls— pyiH)clastics,  autoclastics,  and  sedimentary  rocks  proper. 

The  pyroclastics.  consisting  of  agglomerates,  ash  rocks,  etcetera,  are  of 

*i.r.il.  Survi'V  111'  (':iii:icla,  1SX7,  |>.  '.i'A  F,  »'t<'. 


f 


•    ••.»,  ,         -    •  • 


oiUfilV. 


•>•>." 


'Z^tuli-t  ;""""-^=7-'-''"t'--  "-l-iul  l.un..,.,n  tlH.sul.i..ts 

i—  Mn,Ml:n-  Mo,.|<,sorn.d<  .oul-l  hanlly  Inv.-  1.....,,  Inn-I.-.l  int.     1         r 

"•^  '7"''^-     ''=^»'-"'  • -ti-"^  fansit s  l...tw,.,.n  a,..lo„u..U,.s    ,      fn  ' 

-...lon.eruh.s  with  ..u...rn  p.l.i.les,  .,.iH.  ...i.hn.u  :..  : 

volcaiuc  iimtmuls.lr,,,,  into  thesoa.  '       '"""""*-' 

'Hh"  a..tn,.|asti,.s  a,v  not  very  oxtensiv,.  an.l  will  n.-ivlv  1...  Mu-ntion.-l 
^^;m.p..odu...Il.ytl.eaaio^..f,.n.hi^,a^.lslH.a^nK^ 
'    '  ^'  tho  love)  wh.r.  prossu.v  pn.,!,,..  plastintv,  an.l  t  .iv.a  hint 


iiHMitioiuMl,  ar.'  the 


-     .own  to  nus  onntfn,  ,1,.  .ruptivos  alr.a.ly   ..,,.,,,,  „,, 

n.H..st.,n..  hro,.c..a.s  ot  St.ep  RuHc   ia|<o  and  rortain  n.n.lon.erates  to  L 
s-n  a  nule  wostof  Fort  Fran,.c.s.  wIum-«  in  tho  sharp  lol.Hn.  n  t 

..    san.  ston.  ..tw...  lay.rs  of  sH.ist  the  latt.r  has  yiH.ir.|  p    s  r 

u  loMu.r  was  i,ro,<.n  to  fra,nu.nts  now  ,.n.l.,..,...d  ,  Jpehhlos  [^^ 


I  1...  ordinary  Hashes,  tr,..  s,.,|in„.nts,  ar.  orsp...iai   intnvst  as  .ivin-. 
e  ear  .,  eas  o,   the  ,.on.liti..ns  of  ,h..  .inw.  an.!  so  will   h.  .l..s.ril   -.f   .   ^ 
at  length  than  the  two  previous  .roups.     The  Keewatin.  tho  .      v    v 
h  -Koly  o     ernpt^vo  origin.  ....ntains  in.portant  s,.lin.en,   rv  n^  >S 
and  the  Loueiuehmg  is  wholly  sedimentary.  '  ' 

KKF.WATIS  IIOCKS 

The  wator-tbrined  rlasti<.s  ofthe  Keewatin  areofunvat  varietv  inelu.l 
n.g  Inuestones.  slates,  ,uartzites.  ,rits.  .raywaekes.  I.reeeias,  a  "  i  p      t 
and  houlder  eon,   .n.erates.     The  lin.estones  are,   however  of  l"' 

U'OL  hen,,     .nnd  ,n  any  thiekness  only  at  Steep  IJoeIc   lake.  7,.  n    U. 
east  ol  i.nny  lake,  wh.re  there  is  a  sn,all  area  dillerin.  hoth  petro-r.,     . 
|-ny  and  strnetnrally  tronMlH.  rest  or  ,h..  .,,i..n/  Tln.s.';ii;;;;^ 
.ave  a  very  n.odern  look,  hein,  seareely  at  all  erystalline  in  appearance 
iKmn,  ..herty   layers  ,n  ,ray  lin.estone  at  son.e  points  an.l   lIlLk    v^^: 
•jH  ......eeous  h.ls  at^.,th..,..     One  alnu.st  exp.^ts  to  .liseover  Ibs^iJ  " 

then,,  hut  none  l,av.>  h.HM,  found.     Thev  have  hee.i  fol.le.l  in  an  ext,-vo  • 
<l.na,-y  way  into  an  antieline  and  syneline  havin,  their  axis  inelin.  H  i 
or  moi-e  degrees*  miMio  oi) 

Theslatcsare  wi.lesprea.l,  passing  oCten  into  phvllites.     .Manv  ..f  then, 
.'ontan,  earhoua.'eous  .natte.-,  and  .son.e  exa.nples  have  a  ,raphitie  1... 
and^.MHlK.Jin,ers.     One  ot"  the,n.  n-o.n  an  u.lab'sis  hy  i;;.  la^^:;^ 


•J2»l 


A.   r.  (OI.KMAN — CLAS'llC    III  IU»NIAN     UO(  KS. 


touiid  to  (•..iitiiiii  7.11  iMT  (•(.iit<)rcarlM.n,i\n(l  is  porous  as  tliou^'li  liydro- 
carlions  liail  volatilizi'tl  Icaviuf,'  roiinl  cavilii's.'^ 

'riM'so.arl.oiia.fous  slates  may  l.c  company  with  tlif  i)lack  hIuIc  of  the 
Su.lhury  n,-ioM.  in  wlii.h  Dr  Kllis  has  f(.uiul  ('..S  per  (•cut  of  carhoiMUul 
whirh  was  at  one  time  l.ilumiiious.  as  shown  in  Halt'our  township  l.y  a 
larire  vein  of  anthraxolite,  once  no  doiil.t  a  Ihiid  or  i.histie  petroleum 

product.! 
The  widespread -ray  wackes  need  o.dy  h(Mii<'ntioMe<l,  since  they  present 

no  points  (.1'  special  interest,  and  the  same  may  he  said  of  the  somewhat 
unusual  qiiartzites  and  ^rits,  hut  the  con^ilomerates  are  of  more  impor- 
tuuee.  Thev  are  iounil  in  many  localities,  hut  only  one  example  will  lie 
taken  for  dJscrij.tion,  that  of  Shoal  lake,  more  thorou-ldy  studinl  than 
the  others  hecause  occurrinij:  close  to  a  numher  of  ^old-hearing'  veins. 

As  .seen  on  the  shore  of  the  lake,  it  is  a  Bchist-con^domerate  consisting 
of  ^q-een  chlorite  as  a  matrix,  with  well  rounded  pehhles  of  all  sizes  up 
to  two  feet  in  .liameter  emhedded  in  it.     That  this  portion  of  th«  con- 
glomerate has  underjione  shearing  is  slu.wn  l.y  the  llatteninK  an.l   even 
tailinji  out  of  .some  (.f  tne  softer  pehhles  and  the  hreakin-?  and  shifliuK 
of  the'i.arts  of  some  of  the  harder  ones.     The  <-ommonest  rock  species  in 
{\n-  pehhles  arc  (piartz  porphyry  and  i.orphyrite,  felsite,aiid  «;reen  schists 
indistinj,niisliid)le  from  adjoining'  Keewatin  schists.     In  addition,  there 
are  fra^nnentsof  hlackand  red  (luartzite  and  of  white,  pulverulent  .sand- 
stone, of  vein  (juartz  and  of  anorthosite.     No  gneiss  or  granite  has  heen 
found  after  careful  search,  though  some  (lua^lz-porphyries  having  the 
crystals  of  felspar  and  dihexahedra  of  quartz  much  crowded,  look,  at  first 
glance.  v.M-y  like  granite.     Most  of  these  pel)l)les  are  easily  matched  hy 
Keewatiii   rocks,  sometimes,  however,  many  miles  distant;    a  few  are 
evidently  t'oucliiching.  and  none  are  Laurentian.     One  rock,  a  ([uartz- 
parphvrv.  half  ma<lc  up  of  heautiful   spherulites  having  feathery  inter- 
growths  of  .piartz  and  felspar,  has  not  hitherto  hecn  recognized  in  Ontario. 
Two  or  three  miles  north  of  Shoal  lake  and  some  distance  across  the 
strike  the  n.rk  hccoiues  much  less  schistose,  has  a  coarse  grit  as  matrix, 
and  might  almost  he  (lescril)ed  as  a  hreccia,  since  many  of  the  pehhles 
arc  scan'cly  rounded.     The  pehl)les  are,  however,  of  the  same  rock  si.ecies 
as  those  on  the  sliore  of  the  lake. 

This  hand  of  conglomerate  is  at  least  K)  miles  long  and  2  miles  wide. 
Its  thickness  can  hardly  he  less  than  a  mile  and  may  he  almost  douhle 
that,  since  the  dip  is  steep,  hut  a  covering  of  sand  [.revents  very  accurate 
measurements  of  th(!  width.  A  very  similar  conglomerate  appears  on  the 
east  shore  of  I'ppcr  .Maniti.u  lake,  ")(»  mil.'s  to  the  north,  containing  por- 


*(Jfol.  Siirvi-y  of  Ciiimila,  1HH.\  PP-  f'".  12+,  nnd  loO,  CC. 

toiiliirio  Hun'Mii  of  Mim^^  U.'lMirl,  Iwic,  p.  I.V.i,  <'tc..t..ni. 


^ima 


KKKWATIN    ASK    rn|  (  ||  I(  M  l\(i    ItocKS. 


'>'>: 


J'l.yr.y  l,.|sit...  .,i,M.f/.it,.,  ,.tr..tn-a,  un.|  a  (ino  ,.xan.|.l,,  is  fouiul  at  I{at  Per- 
tu..'.-.  tiK.  n.atnx  ...  this  ..„•..  I.uuvv.t.  Im-!,,.  s,.,i..iti,.  insfa.!  ufrhlnritic 
Numon.iw  other  n.stan.u.s  a.v  fouM.i  in  various  parts  of  tlu-  rcKion.     No 

'';:  ■  ''"■^  ^;'  "•••' ;""  " >"''l'"'l>-  ''^"uvntia.,  l.avo  iKMM,  reported  fron,  unv 

'•1  <l'|-'".  though  ^M'a.nte  hoMl.h.rsare  rou,nl,as.  fur  exainph..  near  AhranH 

Z'n''n      ;'"'''•''''''''"'■■    ''''"•>•  ■•-'•"'•'-■''-ly.'n.ptive.ranitoH 
..e.ni  ^.  the  Keewat.n  „,  ..ei.,!.l.orin;.  inralities.  an.l  .iiller  in  appearanee 
"■""I  the  clianieteristie  },'raiiite  of  ih(!  Imurentian. 

rnniiiriilMi  Iim-K.^ 
'I'la-  ('.......hiehin,!,'  rocks  are  ail  lornn.l  of  san.l  or  ehivev  san-l  more  or 

U-ss  n.etamorph..s.,l.  The  least  ehan,,re.l  werefo.nnl  hv' the  writer  on  the 
HlM.re  oi  I.an.y  rn  er  a  n.ile  l.eluw  Fort  Fran,-es  a.ul  at  the  Seran.l.le  nm.o 
near  Kat  I  ortaj,'e.  Tiiey  lorn,  thin  Ih.Is  of  yell,.wish  or  l.rownish  soft 
san.lstone  lynifr  I.etvveen  n.ieaeeons  an.l  ehloriti.-  sehists.  I'nder  the 
"Men.seope.  hesi.le  jrrains  of  .p.art/,  there  are  partieles  of  magnetite  an.l 

"iMnerons  sn.all  prisn.s,  pro! ly  of  tren.olite.     In  .enerul,  however,  the 

(  ou.h.eh.nfr  consists  of  hiotite  sehist  or  j,meis.s.  the  .pmrt.  showin-^  a 
castK.  or,j,nn.     Some  of  these  schists  contain  sillin.anite;  more  rarelv 

Ihey  appear  as  tiH.rouuhlycrystalliMejrneiss  containing  nu,s,.uvite.,niero. 
cln.e,  etcetera.  reseml.Iin^  the  adjoining  Laiircntian  and  lorming  transi- 
tions toward  it. 

The  Couchiol.inK  inelu.Ies  no  ..oarse  elasti.s  and  is  nowhere  separated 
from  he  underlyn.fr  F.aurentian  l.y  a  i.asal  eon^domerate.  These  rocks 
luive  b,.en  mapped  l.y  F,awson.  Snuth,  and  Mclnness  as  coverin-^  exten- 
sive areas  in  the  southern   part  ..f  the  re,,ion.     l{ocks  of  a  si ar  'kind 

'•••'•ur  on  Mamtou  lake,  near  the  lake  of  the  Woods  and  at  other  points, 
I'lit  have  not  l.eeii  separated  in  the  mappinj^. 

IvKl.ATIoN    OK    KkiaV  ATIN    To    ( 'on  II  KM  l.Nd 

F.iwson  su-ests  that  the  Shoal   i,ake  and  otl,,  r  conulmncratcs  repre- 
sent the  hascof  the  Kccwatin,  and  so  indicate  an  un,.onforn>itv  hetween 

thekccwatmand.lH.Couchichin.-^Muitthclindin.M.fmanvKeewatin 
peN.  es  ,n  the  e,.„glomerates  opposes  this  view.     .\   striking,  evi.lence 

hat  the  l.reak  represented  l.y  these  conglomerates  comes  hi,d.  up  in  the 
ke..wat^.n  uistead  of  at  its  has,,  just  ahove  the  (V.uchichin^  is  to  he  thund 
at  Shoal  lake,  where  a  d^sy  i.oulders  of  coarse--i  lind  anortho:ute  found  in 

he  schist  con,i,domerate  are  exactly  like  portions  of  a  hoss  of  an<.rtho.ite 
two  nules  away.  As  this  anorthositc.  an-a  contains  masses  a.id  strips  of 
eharactenstic  Keewatin  sehist  swept  olV  durin-  its  eruption,  it  is  evident 


♦linil.  Siirvrv  of  (mm;!!!,'!,  Inst,  ;>,  si,  K, 


''2S 


A.    I'.  «n|.i;.M  AN — <  I.ASllr    ||i  litiM  AN     lioi  KS. 


tliat  ill)  iip.iiiciisc  liipst' itf  tiiiir  s(>|i:ir!Ut's  tliP  (■oii;,'|<)iii(>nitf  iind  tli*'  un- 
tlorlyiii;;  Kcfwaliii.  loiii.'  ciioiiu;!!  I"i"  ii  cinirsc-^'niiiicil  iiliitunic  rock  to 
Hitlidily,  |ii'nl>al>ly  nt  ciiiisidcnililf  (lc|itlis.  ami  tlu>n  lot-  tlic  i-t'^;ioii  to  lio 
so  |irol'oiiii(lIy  irodcil  as  to  inciviilf  |ii'l>l»l('s  of  tlir  iiliilnnic  rocU  on  a 
sfashoi'c.  It  is  prolialtlf  that  llic  Kecwatin  coii^loiinTatcs  wliicli  liavo 
lu'i'ii  rcrcrrfd  to  ivpri'Sfiit  an  iiii|»oitaiil  iiilcrval  of  erosion,  |M'rlia|is 
«M|uivaicnt  to  the  one  sho'i.  n  lo  cxi-  liy  \'aii  llise  and  (tthui'rt  ludwiion 
till'  ii|i|prr  and  Iowit  lluronian  in  tin-  .stiiU's  to  the  south.* 

Ncvi'i'tliflcss  tin'  strilvinij,  dillri'i'ni'o  in  tin'  cliarai'lfr  o|'  tlic  rocks  ol"  the 
two  scries,  wholly  sandy  scdinn-nts  in  the  CoiU'liicliinj.',  largely  dialiasi; 
and  |>or|ihyry  and  the  products  of  their  alteration  in  the  Keewatiu, 
shows  that  conditions  had  greatly  chani^cd  Iteloris  the  lat''r  series  wan 
I'oi  ined. 

It  must  not  he  assumed,  of  course,  that  all  oi'  the  erupti\es  tound  in 
the  Keewatin  were  surface  Mows  of  the  sanus  ui.'<*  as'  the  enclosing  rocks. 
Many  of  them  arc  prolialiiy  <>(  the  nature  of  lac(!(<litic  sills  like  the 
trap  slu'cts  in  the  Aninukie  near  Thunder  iiay.  In  fact,  hut  for  the  un- 
doul>ted  pyroi'lastit:  rocks  anion;.;  the  seiliments  oiu;  mi^iht  sus|iect  that 
most  of  tlcm  were  injected  hetween  the  sedimentary  heds,  perhaps  at  '■: 
much  later  dale.  <ince  no  aii'Vi^daloidal  varieties  have  liccn  found.  In 
a  reirion  where  there  has  ix'on  so  much  foldiiii;  and  shearing'  it  is  rash  to 
make  positive  statements  mi  such  matters,  however. 


% 


'rmcKNKss  Ol'  TiiK  llruoNiAN  Skuiks 

I.awson  estimates  the  thickiie-<  of  the  Keewatin  at  alxiut  ')  miles,  j"  and 
of  the  CoUclMchiiiL;-  at  alxiut  the  same  ;  I  hut  W.  II.  ('.  Smith  su^'<j;ests  for 
the  latter  that  tlu'rc  may  lie  a  iiumlx'r  of  closely  appressed  folds.not  easily 
separated,  so  that  the  thickness  of  the  ( 'ouchichiiii,'  may  he  very  n  uch 
less,  thoujih  still  reaching'  S.Odd  ,,r  '.>.("»()  fect.^ 

Kollowiii'.i  l.awson's  estimate,  the  two  series  to^fclher  sum  up  to  od.OOO 
or  more  feet  in  thickness,  thoU'.:h  it  is  prolial)le  that  the  lowest  heds  of 
the  ('<  uchi<'hini:-  have  lieeii  dissolved  liy  the  iiiolti'ii  l.aureiitian  rocks 
lieiieath.  since  no  liasal  conglomerate  has  hccn  found  ;  and  also  that 
there  has  liecii  a  coiisidci'alile  amount  of  compi'cssiou  diirin^j;  the  sipiecz- 
in.r  underL^one  in  liie  sliar|i  synclinal  folds,  as  proved  l)y  the  llattening 
of  soft  pelthlcs  in  tlie  conglomerates. 

The  Couchichinir.  containing  some  little  consolidated  sandstonen,  can 
scarcelv  he  included   in  the   Laurcntian  :  and  as  it  forms  transitions  to 


♦.IninilMl  III'  lir(p|..L'V.   vol.   i.    No.  2.   p.    I'JIP. 
+  1. •■<■!.   SlirVl'.V  of   (    ;lllilllil.    INNT,   |l.  ■'I'l,    I'". 

;  Uihi..  pp.  nn  mh.i  \i<:.  v. 

'.  IImiI,,  1m»i-'',i1,  pp.  M  and  .v.,  (i. 


inKKNKSS    AM.    llM->    I!  Kl  ATIUX. 


.M 'ii::,,i  „:  i,,,;;:;  ■  .r;;-'™  "■■  '■- ■■■'  "■■■  '"■■  '"»•■"■•-  -I'-m 

,-     .        II  .IS  III,.  .\|.|.iiliicli)iiii,s  mid  tlic  Kockifs. 
Kii;....  I!i.;i.ATi..Ns  n,.-  laruKMiAx  am.  II,  ,.,man 

'■'■■I'"'-' V.  ,i,.  „.,.  .,■,.,,  ;■ ;  ;',.",":;"":'";■■>• ""'  '■■■ 

i:;'n^':sJ::;:i:';,;vl"r 7'''-'' "..'-- :;:;::;;;:; 

-■^'■^, -■--.". ''M:;;;;t;::;;:;i:n  ;,;:;:;:r:'''-';'''r«" 

"'  Si-...iit...|.,- it,,,,,-  r,.|»i„.  ,.,,,,,,..,11,  ,,"     ,,    ■'"'".->'  .I.';     Hikes 

11.11 h„.     WluT,.  tl„.  kfl,.,- i  ■  k-  ll.c  «,„,„»  „„„  11,^, 

lllr   Iluroiu;;;,  Hchist.s   haVf  ;illUu-||     •.Ki-,,-.    ,     ..  i- 

(•..-i.s,  H.'!,!,..,,  I,.ss  il,„„    I,-,  ,1,  .         ,'       ■,   "  """''.  ''''■  '"'">■  '"""  ll.« 
i..(....l...l-|.sv,„.,h„.  ■  ■""'  "  '■'■" '■ I  ."■-  '■'.I.le.l 

.ii.';;:.::':::;:;:':;'';;:;,,';;:::;/;:;;;':;:'':;:-'^' :".-.M...si„ 

'■""" r..n,.,   ( I  .JnnlZZ,'7"- "":'"'  "'"""' 

I....R  ir...,.  ,■;,»,  „,  ,v,.,l  ,„„|  ,.-,  ,,i,|„ ,  , ,  „,„,..        •,,"'-"'-\.;"'  ","l.«' 


liikf  of  tlio  \\'o(»( 


,„,.,.         '':  =""'  111  tlu.lJnm.l,.  I'lvs.iu'iU.  „r  tj... 
'-i''nnlosnUn,,t!MVoM..ast,owostan.l/.h:;-u;: 


*•"■<. I,  Siir\ 


"'■\  "I  <'aM!i  Im,  I.snT,  |..  Ill',  K. 


230 


A.   1'.  (  (iI.KMAN — CLASTIC    rirUONIAN    HOCK'S. 


Ol'  the  sinallcv  arcMs  niontioii  iiuiy  Ue  iiiiulc  of  Sultiina  island  a  tew 
inilt's  iVoin  Rat  Portajie.  I'ainous  for  its  <;()ltl  mine.  Here  a  boss  of  coarse 
])or|)hyritie  <i;ranitoi(l  f^neiss  a  mile  in  len<fth  by  lialf  a  mihi  in  width 
prose  '.ts  the  same  eruptive  contact  witli  tlie  1,'reon  Keewatin  rocks  as  one 
finds  arounil  the  laruer  masses.  Another  simih\r  boss  of  coarse  Lauren- 
tian  jiranite  was  found  by  the  writer  at  Caribou  hd<e,  east  of  the  lower 
end  of  lake  Manitou,  the  area  bein^  only  about  a  scjuare  mile.  Exam- 
ples of  intermediate  sizes  may  be  found  on  the  Canadiar.  Geological  Sur- 
vey's maps  of  the  region. 

Finer  grained  granites,  generally  showing  no  foliation  on  the  edges  of 
the  areas,  are  common  also  both  in  Jluronian  strips  and  in  the  I.auren- 
tian;  and  many  more  small  knobs  and  bosses  tlian  were  mapped  by 
Lawson  in  Ins  somewhat  hurried  work  will  be  found  from  time  to  time; 
such  as  the  area  of  protogine  containing  so  many  gol;l-bearing  veins  at 


lAUfteNTIAfi 


GlIANI  TL 


Kna  UK. 


ScALt   or  MiLtt. 

-(iruhi'iiriit  Miiji  nf  I'ait  nf   W'l  stint  Oiildriti. 


Shoal  lake.  So  far  a.s  known,  these  granite  bosses  are  later  than  both 
Keewatin  and  Laurentian,  having  penetrate-'  both.  It  is,  however,  not 
alwavs  easy  to  say  whether  a  given  rock  is  Laurentian  or  a  later  granite, 
and  it  is  likely  that  *lie  two  are  connected  in  origin  and  might  be  ar- 
ranged as  a  consecutive  series.  Both  Laurentian  and  other  granites  send 
off  felsitic  dikes  into  the  adjoining  rock,  and  in  this  way  one  may  often 
discover  the  proximity  of  a  gneiss  or  granite  area  a  ([uarter  of  a  mile 
before  reaching  the  contact. 

It  is  worthy  of  note,  as  observed  l>y  Lawson,  that  often  the  gneiss 
throws  darker  and  more  liasic  near  the  contact  with  basic  Iluronian  rocks, 
as  though  some  of  the  latter  material  had  been  incori)orated  in  the  un- 
derlying Laurentian. 

The  accomjiiuiying  map,  figure  1.  will  ilhistrate  the  geological  relati(m- 
shii)s  just  mentioned.  It  has  been  ]>antogra|»hed  from  tliree  map  sheets 
issued  bv  tlu!  Canadian  (biological  Survey— the  Rainy  Lake,  Seine  River, 


I 


I'IKI.I)    I.KT.ATroNS    AM.    SKCTfONs. 


2.'U 


90 


-e,„e,l  ,vi„e  t„  „  .      ,''       ^  l'  :'::;?-"'''''''  »'■«  '■"■"Pli-te.l,  it 

B«>l<.sical  l,„un<i.„-i,.,     'fiV  "'l'"»'"l'l'.v  »"  as  „„l  t.,  ,■„„/■„,„  tlie 

a...l  .v«t>v„„l,l  s    «t,        .    """'';;■"';<»': 'l"'"Bl'  tm..t,  t„tl,o  m.rtl, 

...■«;l:t.":;::;;,,ji;:::;:'.  '7'""'  i'«-""""  i--"» « -t  ,„. 
rtir;::;.r-;;;;;S!-::7f"-'r-™™-'^- 

1>«-  va„i8l,e,l      I,„.„        ,"      *"  "•""":"'""■  ""■  '"'""">  of  "«  imrt  that 

"....,.>et., we ,1';  I 'rix'':;;!'"- ■;.''"'■  '■■■;"■"' "■"""'"»' '"'"» 

v-.vi.,,.  rr„,„  I  n.ik.  t„  r,o  „  I  .!     w    ,  T,  ''^ ',    """  '"  '""""■''^'■'' 

'"»■■»  of  i„oilo„  ,-ocl<  wan  l„,,„,l  l,a.„,|      '""'^""'"  ""'  "'«  "l.-l»«h,i>K 

Wcatiii  through  which  tlicv  ri...      t  .,,.  i     ,     •* '  V''*'^'^'^  «^  the  kee- 

ortl.o.te  bo.  ,.  the  stu„,„  „ra  volca„o  ,-„,.„U„i,„  t^^  'l^'jitir* 

(iKf)r,0(;i,-Ar,  IIisTouv  ,„.-  thk  R|.:,ii,)N 

IfevHMvin,,.  the  facts  prese.ite.l  l,y  the  n.cks  of  western  Ontari,,  «■    r     . 
-^^^i-tHenes^Couchi^^^ 

*<i.,,,l.  Sii|-v,,y<,f  ('..,„a,|;,,  IwT,  p.  :,7,  K.  ^" 

XX.W-lliu,.  iiK„i,.  S,„:  Am.,   \„,..  :,,  is;,;. 


m 


232 


A.   1'.  (Ol.KMAN— 'lASTlc    III   UONIAN     KocKS. 


cU.posit.cl  .m  a  son  iK.ttu.n.  sinr.  entiroly  .U.stn.y..l.     'rh.  u.ljoiuinK  Huul 
nu.stlKivr  pivs.M.UHl  an  nLundnnce  of  quurtz-beuriug  rucks  to  lunnsh 

so  nianv  cuUic  luiK's  of  san«l. 

Vrterat  least  a  mile  and  a  l.alf  aiul  probably  liv(;  miles  tlucknoss  ot 
tbeso  san.ls  had  been  laid  down  in  the  soutbern  portion  ot  tiic  region, 
the  seeon.l  or  Keewatin  series  began,  in  wl.ieb  great  eruptions  ol  basic 
.,nd  acid  rocks  alternate  with  clays,  grits,  and  congl...nerates,  the  latter 
sometimes  a  mile  thick.  It  is  probable  that  an  important  break  in  ,e 
series  is  shown  bv  the  conglomerates.  During  the  later  part,  il  no  the 
whole,  of  the  tinie  we  may  sui.pose  that  organisms  existed,  turnishing 
the  lar.'c  percentage  of  carbon  found  in  scmie  of  the  rocks. 

ritimatel  V  the  sinking  sea  bottom  was  loaded  with  an  eight  or  ten  iniles 
thickness  ol'  sediments  and  eruptive  materials,  as  in  the  geosynclinos 
preparin.'-  the  wav  for  later  mountain  ranges,  and  th(>  slowly  nsnig  i.so- 
<reotherms  softened  or  fused  the  foundation,  which  rose  into  domes,  tiie 
hmer  i.arts  .solidifying  as  granite,  the  outer  more  viscul  portions  having 
their  constituents  dragged  into  rough  parallelism  with  the  adjoining  .solid 
rocks  and  forming  gneiss. 


COMP.VIUSON     WITH    OTIIKK    RkOIONS 

Th..  usual  theorv  of  mountain-building,  by  lateral  thiust  <lue  to  the 
sinkin..-  in  of  the  earth's  crust  to  conform  to  the  shrinkage  ol  the  interior 
throu'd.  loss  of  heat  or  of  volatile  constituents,  seems  capable  ot  produc- 
i„„  ouiv  folds:  and  it  is  doubtful  if  thrusts  in  two  directions  at  right 
an'des  t'o  each  other  couhl  pro.luce  anything  except  more  complex  forms 
c.f  the  rame  kind.     The  formation  of  irregularly  placed  domes  .lemanus 

some  other  cause.  .  ,    ,,      , 

One  naturallv  compares  these  batholitic^:-- mountains  with  the  lacco- 
litcs  so  distinctiv  bnmght  before  the  world  by  Gilbert  in  his  description 
of  the  llenrv  mountains  of  Colorado.     There  also  there  are  oval  domes, 
though  not  .".ver  M  or  4  miles  in  diameter.     Larger  but  more  irregular  ones 
•ire  described  bv  Whitman  Cross  from  the  adjoining  western  states.     It 
i.  evident,  however,  that  these  cake-like  masses  of  erui-tive  rock  resting 
on  their  undisturbe<l  lloor  of  stratilied  rock  diU'er  greatly  Ir.mi  the  Ilamy 
Lak.'  mountain  stumps,  which  are  only  more  elevated  portions  oi  the 
S-eneral  substratum  of  gneiss  on  which  the  sedimentary  rocks  now  rest. 
The  erui)tive  masses  described  by  Dawson  from  the  Swi'ct  (irass  lulls 
of  northern  Montana,  tilting  up  "the  previously  horizontal  beds  ot  the 
plains,"  so  thai  those  immediately  siin-ounding  the  igneous  masses  rest 


♦  Hulliylit.'  is  tlH'  foviii  (if  the  vvonl  iin'lVir.Ml  l.y  Oanii  :uicl  Zirk.'l. 


COMl'AKISON    WITH    „■,„,,;,;    liK(U()NS 


233 


l!|.„.l  iVii      ,•  ; V  '•"'  '""'""*•'  "1'  ""■  »'""»  into  ,l,„„cs  in  Uw 

I;;;;,:;::,';:" ""— «-i"»t.«etiK.,„,eiv«„„r-,i ,g„,.u 


le 


'''''^'  ;l'>mo  of  tlH.   l^luH.   hills,  us  re,,r.so„t.,l  l-v  Kussell   j  sonns  to 
<'"n,o  rlcsest  to  tlu'  l.iitholitic  .lo.nes  of  westcn.  Onl-n-io   H.   .V  1  ! 

iitu.l  „.|„.t  „n  ivl,„so  t,ls„»  rests  tlic  ,1 b  „f  .„,li,m.„ta,v  rocks  •,, 

:;:;;: \,  ;;,;■;■  r'  'r  t  ""'"-■'*•  '""•■'™"^''  '■■'■ » -'■-'•■  !■'  -i 

htos  .stu,i,,.a  „„  to  ti,„  ,.,.,™t,  a,„i  ,1,0  th„.  or  ti.0  ,„tc,,  ,„.,irt  ,o„.i, 

Cacsk  of  tiiksk  Mountain  Stiu.tuuks 

fJilhert  sus,'ests  for  tl.o  laccolites  that  the  asre.ulin.  fh.,v  of  .nolten 
.        nsesonly  unt.1  the  overlyin,  n.ck  is  U.s  dense  than  itsel.> 
th        U^  ,s  pushed  up  ,uto  a  dou.e.  the  ,eneral  huv  of  hydrostatics  hein 


tlie- 
t  to 


Whitman  Cross,  following  Dana,  does  not  aoeept  the  hvdrostatio  l 
-T.  tlunkn.,  that  the  loree  which  set  the  lava  in  motion  is  sulH  ^^ 
account  for  the  tacts. ||  ^  ■^uiinitn 

I.C.Russell  su,uu.,,sts  "that  uplifts  which  owe  their  orifrin  to  the  intru- 

:";■""  ;"""'^""   "-- 't.  ,herocl<sI.eneaththenM.ete,       d         - 

'•;'"";";'  :;;'^-"f'     ■'■'-y'-'vhe,anciedto..ri,inaterron,th"."    . 

;;''^    •"—'""."'— •"'■-n.st.-.       Methinks.hatthecooli    .a 

.ere.recontracnn,..ustor,l.earU 
.'     '      '"t^-'-'or    s,,ueezn„  upwanl   the  n.olten  rode,  which  nun-  either 

♦li.'ol.  Siirv.'v  of  <Vin,i,|„,  |s,s'.'-'s:i--s|   p'iTc  ~  ' 

f.liMiriialdf  (i,.„|,,t-v.  v.. I.  iv,  riu.  l.  ,,. -i  o(p.    ' 

..•"lo,o-.„  ,1,..   II..„ry  ,„o,„„Hi„s.  Wasl.i,,,,.,',.  ,,:;.  ,',,   I.'    ,!;,',';,;; 

^.'-n, f „„,.  ^;,,;;^, ;;!;.  :;;■;';■ '  '^"'-  ^""'  An.o„H-\v„.„i„„„„, ,.,,, ,,,  ,„. 

♦♦  Ibj.l.,  pp.  |;hi.  1:i|. 


234 


A.  I'.  COI.KMAN— «'I.ASTI<'    lUUONIAN    1{(»<KS. 


Suass  thinks  that  oruptivos  of  this  sort  cannot  elevate  the  roc-l<s  ahove, 
but,  on  the  contrary,  can  (.nly  occupy  spaces  ah'ea.ly  prepared  hy  ten- 
sions in  tlie  earth's  crust.  ^i=  ,.     11     *     4lw> 
So.ne  of  tlic  methods  n^f-rrcl  to   arc  ohv.ously  inapplicahle  to  the 
,,„holitic  tvpe  of  n.ountains.     Russeirs  su-cstion  of  np^ve  l.n^  lavas 
ur..ea  In-  a  's^uee/.inu'  action  of  the  earth's  crust  can  har.lly  he  hrouoht 
to'i.earou  a  region  wlu.v  the  whole  soli.l  crust  for  th.usa.H  Is  ..square 
n,i!,.s  has  l.c.n  tosscl  into  irregular  .lonies.      In  fact  it  is  d.lhcnlt  U.  see 
l,nw  anv  ..ntsi.le  force  can  he  applied  in  such  a  way  as  to  elevate  don.es 
rxi  miles  across  when  the  earth's  crust  a.ljoinin;.- is  itselt  plastic.     We 
seen,  forced  to  look  for  so.ne  force  inherent  in  tluMnas.es  then.se  ves 
If  we  look  at  tlu.  <'onditions  we  Hnd  that  the  granites  ot  these  hathohtes 
w.re    prol.ahlv   fusel    hv.lrothern>ally.   hut   not  excessively  hot   since 
hl,K>ks  of  iKis,;.  Huronian   rock,  readily  fus.-d  hy  a  dry  heat  too  low  to 
melt  -ranite.  often  lie  in  them  with  unrounde.l  ed-es.     Kven  at  a  rela- 
tivelvlow   fusion  point  they  nn.st   have  heen  nu.ch   hotter  and  hence 
(potentiallv)li-hter  than  the  unfused  rock  ahove.  particularly  when  the 
latter  was  i.asic  like  most  mcmhers  of  the  Keewatin  series.      1  his  rela- 
tivelv  li   ..t  sili.'ious  mauma.  prohahly  not  thoroughly  liquid,  hut  only 
plastic,  f..llowin-  the  laws  of  hydrostatics  crept  upward  where  the  loa.l 
of  overlvin.'-  rock  was  smallest,  the  heavier   lluiH.nian  heds  meanwhile 
scttlino-  siowlv  into  svnclines  between  the  risin-  balholites.      1  he  process 
n.av  he  conceived  to  have  -one  on  very  slowly  under  sufBcient  loa.    to 
i.re'vent  violent  disruptions  of  the  overlyin-  strata,  since  a  certain  plas- 
tirity  of  the  heds  is  shown  hy  the  shearin-  ohserved,  especially  among 
the  softer  pehhles  of  the  eon.ulomerates..  _ 

The  lar-e  porphvritic  felspars  ohserved  in  many  of  the  gneisses  and 
..■nnites  -u-.-est  two  statres  in  the  history  of  tlu^se  rocks-an  earlier  one, 
bethre  the  i.scent  he-an.  and  the  later  slow  consoli.latioii.  Augen-neiss 
around  the  margin  of  hatholites  proves  that  th(>  crystals  existed  helore 
the  shcariiii:- uprise  was  complete. 

Some  of  th..  la.rolip.s  .Irscrihrd  by  (liUnTt  slmw  ..nrpnsmgly  pcrhrt 
unl,roi<endonH.sof  >tratilicdrock.and  the  same  is  true  ol  the  domes 
elevatc.l  hv  plutonir  plugs;  in  hoth  ca.ses  Ine,  as  suggested  hy  (ulhert, 
to  there  havin-  hren  load  enough  to  prevent  disruption.  1  he  amount 
„f  stretching  undergonr  by  the  aivhed  strata  in  the  instanres  describe.! 
was,  however,  not  very  great. 

In  the  case  of  the  lai-er  hatholitic  .l..mes  of  western  t)ntario  the  ex- 
tension must  have  heen  as  a  rule  much  greater.  'I'he  (Iran.l  I'resqu  .  e 
dome  may  have  heen  .•omparatively  U.w  ami  llat^sim^'  a  dq.  ot  onh^---l 

*  Antlitz  (ler  Erdo,  vol.  1,  p.  ai«,  ''to 


KXTKXT   OK   TJIK    UKcilOX. 


235 


dc^,^os  ,nay  )..  ,,l>son-o,l  in   Hun.niun  nc-hist  restin.  on  -n.oi.s  at  the 


s 
e 

.St 


eic,  l,lle,l  „  hull.  „„l,.r  tl.o  ...b,.„ltl,..  li,.tl,oli(,.,  it  is  |„,,l„, Hmt  tli. 

l...nt.  was  ,m,cl,  l.igl.er,  „„.]  ll,.  strol,.|,i„,.of  tl,..  „v,.,  vi.,-  «l  -,       , 

'""'" " "'"«'  "■- ' I-  - 1,,,.,,. .i„„„»  iik„  ,i,„t ;,"{i.u.yi,r' 

EXTKNT   OF   THK    liATIIOMTIC    RwilON 

.V.rtwt""r;rr'?"'  J-tory  Ik.  just  lHH.n  slcetch.l  exton.ls 
Com  the  luk  .  ol  th.  \\  oods  on  the  wo.st  to  lac  do.s  MiHe  I.tr.s  on  the  ea«t 

-(»  nules.     .Mo,st  of  tin.s  ]a.-e  extent  of  country  .show.s  the  .ne.;h  stnu- 
t.Te  M,  a  more  or  I.ss  tyi-ieal  way,  thou.uh  toward  lae  des  MiUe  I  aes  on 
the  east  the  l.ands  of  fluronian  tend  to  heon.e  parallel,  su^^^i 
approach  to  the  nu.re  nonnal  lohled  n.oun.ain  structure      ^-ou-W 
th...  whole  rejiionthe  Laurentian  has  eruptive  contacts  witlUheHu 
n.an,a.Kl  notlnn,  liUe  a  hasal  con.lon.erate  of  the   Iluronian  clul  .^ 

It  would  be  unwarranted  perhaps  to  su-est  that  the  relationships  de- 
s<-rd.ed  are  n<,rn,al  lor  the  Archean,  especially  when  relativelv  onl  a 
Muall  portion  ot  the  nun.ense  extent  of  the  Canadian  Archean  has  I.^Vmi 
'"jM'P-1  jv.th  any  detail,  yet  in  a  considerable  nun.ber  of  instances  sinnlar 
relationships  have  been  found. 

Drnvling  n.aps  imperfect  mesh-like  strips  of  Huronian  about  areas  of 
eruptive  gnei.s,s  and  granite  from  the  district  of  Kcewatin  f  SO  miles 
north  of  the  lake  ot  the  Woods,  and  Harlow  .states  that  the  underlvim! 
gneiss  has  an  eniptivec.ontactwiti,  the  Huronian  in  the  Sudburv  region 
•J  . n.h.sto,hceas,  of  lac  des  AlilU.  Lacs.  I  )r  Hell,  however,  appea;::  to 
.1  c.  .on.  Ins  v.cw.  ..xplamnig  the  relation  of  the  two  series  of  rocks 
at  W  ahnap.tae  lor  instance,  by  assuming  a  tault,:  M  v  own  observations 
near. Sudbury  ami  Wahnapitae  convince  me  that  at  tln.se  points  the  con- 
tact is  eru|,t,ve,^sinc^dike^  oO^^egmatite.  etcetera,  may  be  seen  passing 

rn:;-^;j::::;:::';:;;-;:;:;;:;:::;y;;;t:;:--—     -<■■■• -^.^•m.,:.S,s 

t<l<'"l.  Siirvoyof  c.innil.n,  l,s:il,  piirt  K. 
J  IM.I.,  |,S!I(kVi|,  |.,  II,  F. 


236 


A.   1'.  (  nl.KMAN- 


l.ASIir    MI   KttNlAN    i;<)«  KS. 


fnim  tlic  ;j;iii'iss  into  tlic  -rciMi  Iluronijin  rocks.  Tlie  lonp;^  so  oh  a  raot  er- 
istic of  the  iluroiiiMH  I'lrtiuT  \v<'st  arc.  however,  to  l>e  seen  only  indis- 
tinctly, if  at  all.  on  i'.cU's  ina|p  of  the  re^'ion.  .Vdanis  atul  Harlow  show 
the  same  rehilionships  l>ctwecn  the  Hastings  and  Crenville  series  of  east- 
ern Ontario  and  the  underlyiuji  Ottawa  .uneiss.*  and  Adams  maps  sim- 
ilar eurvini,'  hands  of  the  (Jrenville  crystalline  limestones  sinkinjr  into 
tlic  <:neisscs  helow.  in  his  report  on  tlie  Lanrentian  area  north  of  the 
island  of  Montreal. t  Tiicse  two  scries  are  prohahly  the  eastern  c(|uiva- 
lents  of  the  western  lluronian.  the  (ircnville  series  liavinu'  under^'one  a 
more  intense  metamorphisni  than  the  nsual  llnronian.  Tlie  coii-ilom- 
erates  found  hv  .\dams  prove  tliat  tliese  rocks  were  undoiil>tedly  of  sedi- 
mentary origin. 

Still  "farther  east,  in  the  great  Labrador  peninsula.  Lowe  ilescrihes 
crystalline  limestones  and  garnetiferous,  graphitic  gneisses  fornung  l>ands 
in  the  i,aurentian.  tliou-h  his  evidence  as  to  tlie  relatit)!)  of  the  ordinary 
lluronian  to  the  underlying  i^aurcnlian  is  not  so  conclusive,  lie  recog- 
nizes in  some  of  the  mica-gneisses  seilimentary  heds  like  Lawson's  Rainy 
Lake  Conchicliing.  luit  in  other  ]ilaees  speaks  of  lluronian  roeks  as  rest- 
iii'..;-  uiiconformaltlv  on  tlic  Laurciitian.  though  in  some  cases  they  are 
more  or  less  interfoldcd  witii  tlie  Laurciitian.}. 

On  the  other  liand.  according  to  \'aii  Hise.  Logaifs  original  lluronian, 
north  of  the  lake  from  which  it  got  its  name,  seems  to  he  of  later  age 
than  tiic  underlying  Laurentian.  since  1h  linds  l>asal  conglomerates  or 
breccias  containing  fragments  of  Laurentian  rock  at  two  localities. §  Har- 
low, who  has  examined  the  same  region,  thinks,  however,  that  there  also 
the  contact  is  eruptive. 

From  Vail  Ilise's  admiralilc  '•  Principles  of  North  American  pre-Cani- 
liriaii  (ieoloiiy  "  one  linds  that  a  conglomerate  of  the  lluronian  rests  dis- 
cordantly on  tiie  foliated  edges  of  the  I'.asal  Complex  at  many  points 
south  o|'  lake  Supcrior.jl  and  Dr  Dawson  informs  me  that  characteristic 
lluronian  lied- rest  on  an  eroded  Laurciitian  surface  in  New  Hrunswick. 
l\  inav  hi'thal  at  more  southcily  points  the  tliickncs,-  of  the  lluronian 
series  is  coiisiilerahly  less  than  in  tlietypical  Archcan  region. and  hence 
that  the  iloor  on  which  the  sediments  rested  was  not  softened  or  fused- 
as  happened  fartlier  north.  ( )ii  the  other  hand,  it  is  not  impossihle  that 
in  the  states  south  of  the  lakes  n.cks  of  a  somewhat  later  age.  resting  on 
the  uptunictl  edges  of  the  .\rehean  ( including  the  Uainy  Lake  HuroniaiO 
havulieen  looked  on  as  lluronian.     Van  Hise  includes  miea-sehi.sts,  green 

*  Am.  .Iiiiir.  Sri.,  viil.  iii.  M;irrli  iM'.iT. 
+  iiiM,|.  Siirvy  of  CMiiiiila.  is'.i:..  |..irt  .1. 

;(,.■..!.   Sin\l\    ..r  <;im;,.I;i,     Ixi:..   |.:irt    I.,  p.   llHi,  I'll-. 

i  N.  Aim.  I'r.' I  aiiil.|i:iH.  l^'.ii'.  I'.  777. 
"  II. i. I.,  \:  7S1. 


KX'I'KNT    (i|-    Till,    |!|.:(i|(,\. 


237 


H.  ..sts   c.t,.,.t,.n,,,.|    UusuM  in  llH.  nas..,n..n(  (  o.npl-x.  on  whos.  .ro.!..! 

that  .l.stnu.  ly  <■  ...s,,..  n.Ks,  sud.  as  tl,..  littl..  alCrnl  C.nn.lnVi.in.  san  I 

e     ell  lor  :,  small  party  of  A.nonran  an.l  Cuna.lian  ,..olo,ists  int.resLl 
u     Iks.  .„u.st,onsto,o  over  n-rtain  typical   iv^ions  to^.ther,  sc.  as  to 
con  e  to  a  nmnnon  ba^.s  of  .■lassili..ation  tor  tlu..  .liflh.ult  lo.n.ations. 
_    llonvvor  It  may  he  in  other  r.-ions.  there  is  eertainlv  a  verv  lai-earea 

.n.ortlnvest(  nUuMo  inuhielaluM-elationshetween  hatholitJso/;^^^^^ 
.    uul  ,ne.ss  an.l    he  selusto.se  roeks  of  llnrouian  (Ontarian  or  Al.otkian 
age  are  as  ,  esenhed  in  the  lore.oin,  paper.     Tens  of  thousands,  i 

u  M  :  ^''••7":'«' "•  -l^'--'" il-'l'  .1...  western  Iluronian  were 
oMoe  alloat  on  a  plastie  .ranitie  ma,n,a  whieh  swelled  into  .reat  huhhle 

.Icomoun.isMvluletheeohlersuWaeeroekste.uledtosinkiutotlK.  al 
be  weeu  ;  and  a  pheuoiueuon  ol  stieh  wi,le  extent  deserves  earelui  s  t  " 
whether  the  explanation  ^iven  ahove  h,.  eorreet  or  n,.t 

It  IS  worthy  of  note  that  in  several  re-dons  wheiv  aneient  sed-'meuts 
woresupposnl  to  rest  dise.>rdautly  on  the  Fundamental  Complex  more 
detailed  s  u.ly  has  proved  tliat  the  eontaet  is  eruptive.     The  latest  i. - 

tanee  ,.s  descnhed  hy  R.  A.  Daly,  who  finds  hatholitie  guei.s.  pu.hin. 
throned,  overlym-  miea-sehist  in  New  Hampshire  f  " 

It  IS  prohahk.  that  wherever  sediments  aeeunuilate  to  a  thiekness  of 
4.M...no,.   ,o.,,UO  ,eet  the  heds  on  wdneh  they  li..  l^eoine  i!la!:tie  if  m! 

^et    w^  1    tl      "■  !''"■;■  "  •""•••'■^'"""'^"  '•-  ''-'•-"'  '--'n  ..ruptiveeou- 
•acts  Mth  the  roeks  ahove.     As  this  has  taken  plaee  heiieath  every  great 
mountain  ran.e.  perhaps  aided  hy  relief  from  pressure  under  antk.Hue^, 
.  Hd  I,,  no  doubt  .still   akin,  plaee  where  preparations  are  heing  made  for 
the  great  mountain  ehains  of  the  future,  a  ,so-ealled  Fundamental  fom- 
plex  IS  to  be  regarded,  not  as  eharaeteristie  of  great  anti-juitv.  but  as  re- 
.sultii.g  Iron,  a  eert  un  set  of  eonditions  whieh  mav  exist  Vt  an v  age 
I  hi'  ,.hler  mountain  ranges,  having  been  more  deeplv"  eroded,  ^dve  lu,  on- 
portunity  to  study  these  guei.ssic  and  granitie,.ores,  while  in  later  ranges 
hey  are  sti  1  lu.ried  out  of  sight.     It  is  likely,  however,  that  a  ba.sal  sec- 
t.o.i  through  our  pre.seut  mountain  rang,.s  woiil.i  show  long  bands  of 
gneiss  and  granite  rather  than  approximately  eireular  batholites  sueh 
as  we  hnd  in  western  Ontario. 

If  the  supposition  just  made  be  eorreet,  areas  of  the  r.aurentian  or 

H.ndamenta     Complex  do   not   represent  the   earth's   cr.tarnnu,,/cn,,te 

but  are  merely  portions  of  the  earth's  crust,  of  se.lin.entarv  oi-  other 

oru^nn,  whu^h  have  been  buried  deeply  enough  for  hvdrothermal  fusion 


*  Pre-eiimbrimi  {icolotty,  p.  7xi 

t.lniirnHl  of  (i,.„|„^'y,  vol.  v.  n<..  7.  p.  ow,  vW. 


'ins 


A.   t'.  fOI.KMAN — CLASTIC    IK   l!i>M  AN     IKM  KS. 


;,ih1  liMV.'  aftcrwiinl  l..-..iMli>int(TiTcl  l^y  l-.n-  c.mtiiuUMl  .IcMUuliiif,'  i'nivcs. 
(;,Hul  t'Xiimpli's  ..r  wi.k-  iirciis  ,.1'  ^nmitoi.l  n-cUs.  incr^qiiii  at  many  [.oints 
into  jiiu-iss  and  liaviii-  an  cniptivc  c.iitart  with  tlu'  ..vcrlyin-;  rncl;s.  arc 
t(,l.("loUM(l.acc..nlin.-i- tn  Dr  Daus.ui.  in  tli.' C.ast  ranucs  ar.l  Int. nor 
i.latcan  nf  I'.ritisli  C.ininl.ia,-  l.nl  hciv  tiir  I'.asal  C.n.pi.'X  is  ..f  Juiassir 


a-iX'. 


CoNCI.I-niNll    (^nSKIiVATlONS 


It  will  ln>  ..hs.M'vcMl  that  the  term.  Lanivnlian  has  lurn  cini.loy.'d  m 
this  paiMTas  l.aws..nan.l  oth.T  (  ana.lian  nvnlcjists  a,'e  acrustoincd  to 
,.nii.l..vit.inaiK.tn.urai'hi.'alan(l  stnictnral  sens.,  forcrystallini' .Lnicissic 
,„  ..ranith-  rocks  undcrlvin- the  llun.nian.     That  thcs.'  r.u'Us  have  ron- 


si)li(latc(l  at  a  later  time   tlian   tlic    llnn.ma 


n    is  evident,  and    tlierel'ore 


thev  have  not  the   position   in  time   which    I.oiian   supj-osed   when    the 
name  was  -iven.      it  may  he  a.lvisahlc  to  provide  another  .lesi.onatnm 


for  these  widespread  rocks,  which  occni.y  thesame  position  stru.'tnral  y 
and  are  formed  of  practi.'ally  the  sam.'  mat.'rials  as  those  to  the  sonth. 
whose  attitude  with   reference  to  t'.ie  lluronian   correspon.ls  to  Loj;an  s 

orijiinal  lluronian. 

ll.nv  much  of  the  -J.t >()().<  10(1  s.piare  ndh'S  of  the  Canadian  .\rcl.ean 
presents  the  same  relath.nships  as  have  l.e.'n  .U'scrihed  m  this  pai-er. 
•uid  how  much  shows  the  ..rlho,h.x  unconformity  hetween  lluronian 
and  Laurentian  can  he  determined  only  hy  careful  Held  w..rk.  ll  the 
erui.tiv."  contact  is  the  normal  type  and  the  lluronian  whul.  rests  dis- 
eordantlvon  the  I.aurentian  turns. ,ut  t..  he  really  later  m  a,-c  than  Law- 
^..n-sOntarian.wemustl.M.kon  the  (  ouchichinii- series  as  presenting  the 
ol.k'st  known  nu-Us.  This  wouhl  carry  hack  the  ordinary  sedimentary 
deposit  of  sands  and  clays  to  the  he-innin-  ..f  known  K^olo.uical  tune. 


♦  .ii'.il.  Survey  cf  CMiiailM.  l.xsc.,  piii-l  H,  »n.l  IWM,  y:\rt  H. 


i 


1    ( 


'>; 


n  / 


5; 


